Patent Application
20180076647
The present disclosure relates generally to power management, and particularly power management for a battery charger.
Battery chargers, in particular battery chargers for mobile computing devices, are evolving beyond just being responsible for charging a battery when a power adapter is connected. For example, conventional mobile computing devices such as laptop or notebook computers include a dedicated and typically proprietary plug-in port for a power adapter. When the adapter is plugged in to this dedicated port, the battery charger is responsible for charging the battery using the adapter voltage specified by the manufacturer of the mobile computing device, in addition to controlling the supply of power to the system.
Recently, some mobile computing device manufacturers have moved toward replacing the typically separate and proprietary power adapter port with USB ports supporting the newer USB Type C (USB-C) or USB Power Delivery (USB PD) protocols. USB-C supports bi-directional power flow at a much higher level than previous versions of the USB interface (e.g. 5V). Starting from a default 5V voltage, the USB-C port controller is capable of negotiating with the plugged-in device to raise the port voltage to 12V, 20V, or another mutually agreed on voltage, at a mutually agreed current level. The maximum power a USB-C port can deliver is 20V at 5 A current, which is 100 W of power—more than adequate to charge a computer, especially since most 15-inch Ultrabooks require just around 60 W of power.
These new USB-C and other mobile charging protocols thus provide a wider range of variable input voltages (Vin) to a battery charging system, which presents challenges for existing buck-boost charger solutions based on a NVDC topology, among other things.
The present embodiments relate generally to managing power in a system including a battery, and more particularly to a flexible or hybrid battery charging topology for a system including a battery. In addition to being capable of operating in a conventional narrow voltage DC (NVDC) buck-boost charger mode, it is also capable of operating in a new “turbo power buck-boost” mode, where the input voltage is directly fed to the system load, bypassing the inductor. Compared with the conventional NVDC buck-boost charger topology, the flexible or hybrid topology provided by the present embodiments reduces the inductor size otherwise needed to support new mobile charging protocols, among many other benefits and advantages.
These and other aspects and features of the present embodiments will become apparent to those ordinarily skilled in the art upon review of the following description of specific example embodiments in conjunction with the accompanying figures, wherein:
The present embodiments will now be described in detail with reference to the drawings, which are provided as illustrative examples of the embodiments so as to enable those skilled in the art to practice the embodiments and alternatives apparent to those skilled in the art. Notably, the figures and examples below are not meant to limit the scope of the present embodiments to a single embodiment, but other embodiments are possible by way of interchange of some or all of the described or illustrated elements. Moreover, where certain elements of the present embodiments can be partially or fully implemented using known components, only those portions of such known components that are necessary for an understanding of the present embodiments will be described, and detailed descriptions of other portions of such known components will be omitted so as not to obscure the present embodiments. Embodiments described as being implemented in software should not be limited thereto, but can include embodiments implemented in hardware, or combinations of software and hardware, and vice-versa, as will be apparent to those skilled in the art, unless otherwise specified herein. In the present specification, an embodiment showing a singular component should not be considered limiting; rather, the present disclosure is intended to encompass other embodiments including a plurality of the same component, and vice-versa, unless explicitly stated otherwise herein. Moreover, applicants do not intend for any term in the specification or claims to be ascribed an uncommon or special meaning unless explicitly set forth as such. Further, the present embodiments encompass present and future known equivalents to the known components referred to herein by way of illustration.
According to certain general aspects, the present embodiments provide a flexible or hybrid battery charging topology. In addition to being capable of operating in a conventional narrow voltage DC (NVDC) buck-boost charger mode, it is also capable of operating in a new “turbo power buck-boost” mode, where the input voltage is directly fed to the system load, bypassing the inductor. Compared with the conventional NVDC buck-boost charger topology, the flexible or hybrid topology provided by the present embodiments reduces the inductor size and improves efficiency, among many other benefits and advantages.
As shown, system 100 includes a battery 104 and a battery charger 102. According to certain general aspects, during normal operation of system 100, when a power adapter is plugged into port 106, battery charger 102 is configured to charge battery 104. Preferably, in addition to charging battery 104, battery charger 102 is further adapted to convert the power from the adapter to a voltage suitable for supplying to load 118 of system 100, which system load can include CPU 116. According to certain other general aspects, during normal operation of system 100, when a power adapter is not plugged into port 106, battery charger 102 is configured to manage the supply of power to load 118 from battery 104.
Embodiments of battery charger 102 will be described in more detail below. In laptop, notebook or tablet computer (e.g. Ultrabook) and other embodiments of system 100, battery 104 can be a rechargeable 1S/2S/3S/4S (i.e. 1 cell, 2 cell, 3 cell, or 4 cell stack) Lithium-ion (Li-ion) battery. In these and other embodiments, port 106 can be a Universal Serial Bus (USB) port, such as a USB Type C (USB-C) port or a USB Power Delivery (USB PD) port. Although not shown in
Still further, example system 100 in which the present embodiments can find useful applications includes a Type C port controller (TCPC) 112 and an embedded controller (EC) 114. According to certain general aspects relevant to the present embodiments, TCPC 112 includes functionality for detecting the type of USB device connected to port 116, controlling switches associated with connecting port 106 to system 100, and for communicating port status to EC 114 (e.g. via an I2C interface). EC 114 is generally responsible for managing power configurations of system 100 (e.g. power adapter connected or not connected to port 106 as communicated to EC 114 from TCPC 112, etc.), receiving battery status from battery 104, and for communicating battery charging and other control information to charger 102 (e.g. via SMbus interface).
As shown, input node 204 of charger 102 can be coupled to receive power from an adapter via port 106 (e.g. a USB-C port, not shown). In these and other embodiments, an adapter current (Iadp) sense resistor Rs1 is coupled between input node 204 and transistor Q1, and the voltages at either end of resistor Rs1 are provided to input pins or pads on IC 202.
As further shown, the example charger 102 in these embodiments includes a plurality of power switching transistors including a field-effect transistor (FET) Q1, having its drain coupled to resistor Rs1 and its source coupled an intermediate node 206. Another FET Q2 has its drain coupled to node 206 and its source coupled to GND. The charger 102 includes an inductor L1 coupled between node 206 and the node 208. The example charger 102 in these embodiments further includes FET Q4, having its drain coupled to charger node 216 and its source coupled an intermediate node 208. Another FET Q3 has its drain coupled to node 208 and its source coupled to GND. As shown, output node 210 provides a system voltage VSYS, which can be provided to a system load, such as CPU 116 (not shown).
Charger 102 in this example further includes a battery current (Ibat) sense resistor Rs2 coupled between charger node 216 and an intermediate node 212, with the voltages at these nodes being provided to input pins on IC 202. Another FET 214 has its source coupled to node 212 and its drain coupled to the rechargeable battery 104 developing the battery voltage VBAT. The gate of FET 214 is coupled to the IC 202 for controlling charge and discharge of the rechargeable battery 104. For example, when the power adapter is not connected, the FET 214 may be turned fully on to provide power to the system load via VSYS and charger node 216. When the power adapter is connected, the FET 214 may be controlled in a linear manner to control charging of the rechargeable battery 104 by power switching transistors Q1, Q2, Q3 and Q4 via charger node 216.
The FETs Q1, Q2, Q3, Q4 and 214 are shown implemented using N-channel MOSFETs, although other types of switching devices are contemplated, such as P-channel devices, other similar forms (e.g., FETs, MOS devices, etc.), bipolar junction transistor (BJTs) and the like, insulated-gate bipolar transistors (IGBTs) and the like, etc.
According to certain aspects, the illustrated arrangement of inductor L1 and switching FETs Q1, Q2, Q3 and Q4 implement a buck-boost (BB) topology. A BB topology can operate in buck mode when there is “input to output,” in boost mode when there is “output to input” or in buck-boost mode when there is two-way “input output.” More particularly, the four switching FETs Q1, Q2, Q3 and Q4 are grouped into a forward-buck leg (Q1 and Q2) and a forward-boost leg (Q3 and Q4). By operating either leg, this topology can be exploited by IC 202 to operate in forward buck mode or forward boost mode for charging the battery 104. It can also be caused to operate in reverse buck mode to deliver power out of the USB port 106 (not shown) for charging an external electronic device, such as a tablet, smartphone or the emerging portable power bank products that can charge any device.
As shown in
As further shown, IC 202 can receive a Port Status signal, which can specify whether or not an adapter or other device is connected to port 106. This signal can be generated by EC 114 using information from TCPC 112, and provided via SMbus for example. As still further shown, in some embodiments such as that shown in
Among other things, the present applicant recognizes that, in existing BB charger solutions based on an NVDC topology, the inductor such as L1 needs to process both the battery charging current and the system load current. Meanwhile, with the newer protocols such as USB-C and USB PD, input voltages can range up to 20 V, and system power can range up to 100 Watts, even up to 300 Watts or more with some proprietary adapters. For such a range of voltages and power, the choice of the inductor becomes difficult due to the potential for high power ratings. This can lead to designs needing a large inductor size, which adds expense and further leads to higher power loss and low efficiency. Moreover, a wider range of output power capacitors (e.g. coupled between node 210 and ground, not shown) for supporting BB charger operations may be needed.
Therefore, according to additional aspects of the present embodiments such as the embodiment shown in
More particularly, in accordance with the above and other aspects, as shown, IC 202 according to the present embodiments includes a NVDC BB module 220 and a turbo BB module 222. In embodiments, modules 220 and 222 are activated for exclusively controlling operation of charger 102 in accordance with a conventional NVDC BB charger topology or in accordance with a Turbo BB charger topology according to the present embodiments, respectively. In example embodiments such as that shown in
As will be described in more detail below, when module 220 is activated, it controls operation of charger 102 as an NVDC BB charger. As further described in more detail below, when module 222 is activated, it can control operation of charger 102 in various modes depending on various circumstances, including controlling operation of charger 102 using either Turbo BB battery module 224 or Turbo BB adapter module 226 (which can further activate either Turbo BB battery charging module 228 or Turbo BB supplemental power module 230).
Aspects of how embodiments of the various modules of IC 202 control operation of charger 102, including the operation of transistors Q1, Q2, Q3 and Q4, in the above charger topologies and modes will become apparent from the following descriptions and drawings.
For example, as set forth above, the four switching FETs Q1, Q2, Q3 and Q4 according to some embodiments are grouped into a forward-buck leg (Q1 and Q2) and a forward-boost leg (Q3 and Q4). By operating either leg, module 220 can operate the switching FETs Q1, Q2, Q3 and Q4 using signals 302 (e.g. PWM or PFM signals) in forward buck mode or forward boost mode for charging the battery 104 and providing power to the load via node 210 when the port status signal indicates that an adapter is connected.
When the port status signal indicates that an adapter is not connected, module 220 can cause the FET 214 to be turned fully on via signal 304 to provide power to the system load via charger node 216 and VSYS. When the power adapter is connected, module 220 can control FET 214 in a linear manner to control charging of the rechargeable battery 104 by power switching transistors Q1, Q2, Q3 and Q4 via charger node 216.
Module 220 can also cause switching FETs Q1, Q2, Q3 and Q4 to operate in reverse buck mode via signals 302 to deliver power out of the USB port 106 (not shown) for charging an external electronic device when the port status signal indicates that such a device is connected.
As further shown in this example, circuitry 402 provides access to either module 224 or 226 to signals for controlling operation of switching transistors Q1, Q2, Q3, Q4, switches 252, 254 and FET 214, as will be described in more detail below.
It should be noted, however, that when Turbo BB module 222 is operative, either switch 252 or switch 254 may be closed. According to certain aspects, during transitions between switch configurations, switches 252 and 254 preferably exhibit ideal diode behavior so as to prevent current from Vsys output capacitor(s) (not shown) traveling to either the adaptor or to the battery. This ideal diode behavior also eliminates the direct current path between the battery and adaptor. Likewise, during transitions between switch configurations, switches 252 and 254 both preferably also limit the inrush current from the adaptor/battery to Vsys, respectively.
For example,
In this mode, module 224 can operate switching FETs Q1, Q2, Q3 and Q4 in accordance with information supplied by the port status signal for example. For example, module 224 can turn off switching FETs Q1, Q2, Q3 and Q4 and turn on the BFET 214 (perhaps via circuitry 402, not shown) so that only power from the battery 102 is supplied to the output node 210 via charger node 216 if the port status signal indicates that no device is connected to USB port 106. In these and other examples, module 224 can also cause switching FETs Q1, Q2, Q3 and Q4 to operate in reverse buck mode to deliver power out of the USB port 106 (not shown) for charging an external electronic device when the port status signal indicates that such a device is connected.
In this configuration, according to aspects of the present embodiments, Vin is directly fed to the system load. Module 228 turns on FET 214 and operates switching transistors Q1, Q2, Q3 and Q4 in forward buck, boost or buck-boost mode to charge the battery 104 as shown in
Returning to
In general, the criteria for determining activation of module 230 is established based on the system load being greater than the input power supply capability. This determination can be implemented in many different ways, as described in the following non-limiting examples.
In one example, module 602 monitors the input current from the adapter as indicated by the Iadp signal as described above. When the input current exceeds a set threshold (e.g. as determined from lookup table 270 or registers within IC 202), module 602 can set a timer for counting down a certain period of time. The timer can be a fixed timer or it can be a software configurable timer (e.g. via SMbus). If module 602 determines that the input current exceeds the threshold for the configured period of time, module 602 can cause Turbo BB supplemental power module 230 to control operation of charger 102 instead of module 228.
Alternatively to module 602 monitoring input power supply capability, this capability can be monitored by other circuitry, including circuitry outside of IC 202. For example, EC 114 can determine the capability of the adapter connected to port 106, and based on this determination can send a signal to IC 202 and module 602 (e.g. via SMbus) to activate Turbo BB supplemental power module 230 instead of module 228.
In yet another example, module 602 can determine whether to activate module 230 based on interaction with control loops within the charger 102. For example, in some embodiments, charger 102 has three potential control loops, namely adapter current loop, charging current loop, and charging voltage loop, in switcher forward mode. Each loop has an error signal, defined as “Error=Feedback−Reference”. A loop selector in module 602 according to these embodiments compares the three error signals and selects the loop with the smallest error signal as the control loop of the switching transistors.
In these and other embodiments, when battery charging module 228 is operative, if the total power from the adapter reaches the adapter wattage rating, the adapter current loop error reaches zero and is smaller than either of the other two loops, and so the adapter current loop takes control of the switching transistors, which means operating in adapter current limiting mode. If the total power from the adapter never reaches the adapter wattage rating, it will be a decision between the charging current loop and the charging voltage loop. When battery voltage is low, the charging voltage loop error is bigger, so the charging current loop take control of the switching transistors, which means operating in constant charging current mode. Once the battery is almost fully charged, the charging voltage loop error becomes smaller than the charging current loop, therefore the charging voltage loop takes control which means reduced charging current until it reaches zero (because the battery voltage rises to the set reference).
Entry/exit module 602 in these embodiments can use two possible approaches for making a decision on entering supplemental power mode and activating supplemental power module 230 when the total power from the adapter reaches the adapter wattage rating. In a first approach, the decision is based on when the adapter current exceeds the adapter current reference. This can be done with a filtering to ensure it is a legitimate condition and not a blip. Exiting the supplemental power mode would require the adapter current to drop below the reference, with filtering. In a second approach, the decision is based on when the adapter current exceeds the adapter current reference and the battery charging current has reduced to zero. In this situation, the switching transistors have essentially stopped charging the battery and let all the adapter power go to the load, and yet the adapter is still being overloaded, so the battery needs to help the adapter. Exiting the supplemental power mode in this approach would require the battery discharging current to reach zero (i.e. the adapter no longer needs help from the battery).
In Turbo BB supplemental power mode, during which the system load (e.g. including CPU 116) requires power more than the adapter capability as determined by module 602 as described above, module 230 turns on FET 214 and causes the battery to supplement the adapter by operating switches Q1, Q2, Q3 and Q4 in reverse buck, boost or buck-boost mode as shown in
According to additional aspects, module 230 can monitor whether the system load (e.g. including CPU 116) requires more power than the total capability of both the input power supply and the battery. In this situation, module 230 according to the present embodiments can either regulate/limit the battery discharging current (e.g. to protect the battery) or to regulate/limit the input current (e.g. to protect the adapter).
For example, to regulate/limit the battery discharging current, module 230 monitors the battery discharging current Ibat and compares it with a set threshold (e.g. provided by software, such as a signal from EC 214, or by lookup table 270). Once the battery discharging current reaches the set threshold, module 230 uses a close loop control 802 to regulate/limit the battery discharging current at the set threshold. By doing so, the input current (as indicated by Iadp) may exceed its set threshold (e.g. provided by software, such as a signal from EC 214, or by lookup table 270).
To regulate/limit the input current, module 230 monitors the input current (as indicated by Iadp) and keeps it below a set threshold (e.g. provided by software, such as a signal from EC 214, or by lookup table 270) by allowing the battery discharging current indicated by Ibat to exceed its set threshold.
Another way module 230 can protect the adapter is to regulate/limit the input voltage droop. In this example, module 230 allows the load to draw current from the adapter until the input voltage Vin begins to droop. Thereafter, module 230 regulates/limits the input voltage Vin droop at a threshold (e.g. provided by software, such as a signal from EC 214, or by lookup table 270) by allowing the battery discharging current indicated by Ibat to exceed its set threshold (e.g. provided by software, such as a signal from EC 214, or by lookup table 270).
As shown in
Otherwise, the Turbo BB adapter module 226 is activated, and by default module 226 first activates the Turbo BB battery charging module 228 in step S906. Battery charger operations can then be controlled as described in connection with
As set forth above, even while module 226 is operative, the Turbo BB adapter module 226 (e.g. entry/exit module 602) continuously monitors whether the system load is greater than the input power supply capability. This determination can be implemented in many different ways, as described above, such as by monitoring the input current from the adapter as indicated by the Iadp signal to determine when the input current exceeds a set threshold for a specified time. Alternatively to module 226 monitoring input power supply capability, this capability can be monitored by other circuitry, such as EC 114 based on the capability of the adapter connected to port 106. In yet another example, module 226 can interact with control loops within the charger 102 to determine when to enter supplemental mode.
If it is determined in step S908 that supplemental mode is needed, Turbo BB battery supplemental power module 230 is activated in step S910 and charger operations can be controlled as described in
Although not shown in
Although the present embodiments have been particularly described with reference to preferred ones thereof, it should be readily apparent to those of ordinary skill in the art that changes and modifications in the form and details may be made without departing from the spirit and scope of the present disclosure. It is intended that the appended claims encompass such changes and modifications.
The present application claims priority to U.S. Provisional Application No. 62/394,116 filed Sep. 13, 2016, the contents of which are incorporated by reference herein in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| 62394116 | Sep 2016 | US |
